The invention is based on a state of the art as it is known from DE-OS 33 27 134 and DE-OS 33 37 695 (corresponding to U.S. Pat. No. 4,697,527). The outside dimensions are thereby usually determined by the centering diameter of the bearing bracket in the housing, which centering diameter is predetermined by the gear (or rather by the largest gear in the case of several gears), and by the screws which are used for fastening the bearing bracket to the housing and which are arranged on a perforated circle surrounding the centering diameter; because the housing must have a sufficient thickness for the threaded hole for receiving these screws. Thus, a space remains between the (largest) gear and the radially adjacent housing wall, which space is often desired for technical lubricating reasons.
However, in various cases of use it would be necessary to reduce this space to the smallest possible dimension, for example if devices or the like arranged next to or under the transmission leave insufficient space for the gearing. Such a case exists for example in axle drive units for railway vehicles, such as street cars and the like, where there is a trend toward so called low-floor cars. From this results a demand for a transmission built on the one hand to store, because of high drive performances, a large diameter bevel-gear and, on the other hand, however, to keep the bottom wall of the transmission as close as possible to the gear.
Therefore, the purpose of the present invention is to provide a transmission of the above-mentioned type such that the (largest) gear is to be arranged as close as possible to the radially adjacent housing wall or the bottom wall of the housing, so that substantially only the diameter of the (largest) gear and the wall thickness in this area are decisive in determining the outside dimensions of the housing in the respective radial direction.
This purpose is attained with an axle support structure which significantly reduces the outside dimension of the housing by the otherwise existing radial distance between the gear and the housing wall.
A preferred field of application for the invention is as an axle drive unit for railway vehicles. The drive shaft for such units can thereby be a hollow shaft surrounding the wheel-set axle. The housing wall forms in these cases the base or bottom wall of the transmission housing. The invention assures that the smallest possible distance exists between the axis of the hollow shaft or the wheel-set axle and the underside of the transmission housing, while simultaneously providing sufficient safety against leakage at various points in the transmission housing forming an oil pan.
A further advantage of the inventive construction of the transmission housing is in the savings in weight, a plus point which, particularly in the case of railway vehicles, is not to be undervalued.